JP2013024162A - System for controlling number of compressors - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system for controlling the number of compressors that is capable of quickly correcting the difference between the discharge amount of a compressor and the use amount of a compressed-air-using apparatus, and suppressing pressure fluctuations.SOLUTION: One compressor is stopped when the pressure detected by a pressure sensor rises to or above a number decreasing pressure A, and if a pressure greater than or equal to the number decreasing pressure A is still maintained, one more compressor is stopped each time a prescribed interval elapses. One compressor is stopped without waiting for the prescribed interval to elapse when the pressure detected by the pressure sensor rises to or above an immediate reduction pressure C in a region where the pressure change rate ΔP is greater than or equal to a set value (+ΔP1). In addition, one compressor is started when the pressure detected by the pressure sensor falls to or below a number increasing pressure B, and if a pressure less than or equal to the number increasing pressure B is still maintained, one more compressor is started each time the prescribed interval elapses. One compressor is started without waiting for the prescribed interval to elapse when the pressure detected by the pressure sensor falls to or below an immediate increase pressure D in a region where the pressure change rate ΔP is less than or equal to a set value (-ΔP1).

Description

  The present invention relates to a compressor number control system that includes a plurality of air compressors and changes the number of operating compressors according to the use load of compressed air.

  Conventionally, as disclosed in the following Patent Document 1, it has been proposed to change a pressure threshold value for increasing or decreasing the number of operating compressors based on a pressure and a rate of change thereof.

  Further, as disclosed in Patent Document 2 below, when the compressors are sequentially started or stopped, it is usually performed with a predetermined grace period.

JP 2007-120497 A (claims, paragraph numbers 0140-0155, FIGS. 15 and 16) JP 2010-190197 A (paragraph number 0006)

  However, if the pressure change rate is large and the compressor is about to be far away from the target pressure range, the compressor discharge amount of the compressor is kept waiting until a predetermined time elapses to start or stop the compressor sequentially. And the difference between the usage of compressed air usage equipment cannot be corrected quickly.

  The problem to be solved by the present invention is to provide a compressor number control system capable of quickly correcting the difference between the discharge amount of the compressor and the use amount of the compressed air utilization device and suppressing the pressure fluctuation. is there.

  The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 is directed to a plurality of compressors, compressed air supplied from these compressors, and compressed air to a device using compressed air. A pressure sensor for detecting the pressure of the compressed air, and a unit controller for changing the number of operating compressors based on the detected pressure of the pressure sensor and its rate of change in pressure. The controller stops one compressor when the detected pressure of the pressure sensor becomes equal to or greater than the pressure for decreasing the number of units, and activates one compressor when the detected pressure of the pressure sensor becomes equal to or less than the pressure for increasing the number of units. However, when the pressure sensor detects that the pressure detected by the pressure sensor is equal to or higher than the number-decreasing pressure or equal to or less than the number-decreasing pressure, one compressor is stopped or started every time a predetermined time elapses. However, in the region where the absolute value of the pressure change rate is greater than or equal to the set value, if the detected pressure of the pressure sensor is equal to or higher than the pressure for immediate decrease or equal to or less than the pressure for immediate increase, it does not wait for the predetermined time to elapse. Furthermore, the compressor number control system is characterized in that one unit is stopped or one unit is started.

  According to the first aspect of the present invention, when one of the compressors is stopped when the detected pressure of the pressure sensor becomes equal to or greater than the pressure for decreasing the number of units, and the pressure for decreasing the number of units is still maintained, the predetermined time (continuous stop prevention time) ), One compressor is stopped each time, but in the region where the absolute value of the pressure change rate is equal to or greater than the set value, if the detected pressure of the pressure sensor is equal to or greater than the pressure for immediate decrease, the passage of a predetermined time is awaited. Stop one vehicle without any problems. In addition, when the detected pressure of the pressure sensor falls below the pressure for increasing the number of units, one compressor is started. If the pressure still remains below the number for increasing the number of units, the compressor is turned on every time a predetermined time (continuous start prevention time) elapses. One unit is activated, but in a region where the absolute value of the pressure change rate is equal to or greater than the set value, one unit is activated without waiting for the elapse of a predetermined time if the detected pressure of the pressure sensor is equal to or less than the pressure for immediate increase. In this way, when the rate of change in pressure is greater than the set value and is about to depart from the target pressure range, one unit stops immediately above the immediate decrease pressure without waiting for the elapse of a predetermined time, or immediately Since one unit is started below the increasing pressure, the difference between the discharge amount of the compressor and the usage amount of the compressed air utilization device can be corrected quickly.

  The invention according to claim 2 is such that the pressure for reducing the number of vehicles as a boundary value for determining whether or not to reduce the number of operating units by the number controller is set to become lower as the pressure change rate increases to the plus side, The number-increasing pressure as a boundary value for determining whether or not to increase the number of operating units by the number controller is set to increase as the pressure change rate increases to the negative side, and the detected pressure of the pressure sensor is set to the number When the pressure exceeds the pressure for reduction, one compressor is stopped. If the pressure for pressure reduction is still maintained, the compressor is stopped every time a predetermined continuous stop prevention time elapses. In an area where the absolute value of the rate is equal to or greater than the set value, if the pressure immediately exceeds the pressure for immediate decrease set higher than the pressure for decreasing the number of units, further waiting without elapse of the continuous stop prevention time. When one unit is stopped and the detected pressure of the pressure sensor becomes equal to or less than the pressure for increasing the number of units, when one compressor is started and still maintains the pressure for increasing the number of units or less, a predetermined continuous start prevention time elapses. One compressor is started every time, but in the region where the absolute value of the rate of change in pressure is greater than or equal to a set value, the continuous increase pressure is less than the pressure for immediate increase set at a lower pressure than the pressure for increasing the number of units. 2. The compressor number control system according to claim 1, wherein one more unit is started without waiting for the passage of the startup prevention time.

  According to the second aspect of the present invention, the difference between the amount of compressed air discharged by the compressor and the amount of compressed air used by the compressed air utilization device is detected by the pressure change rate. By changing the threshold value of the pressure at which the machine is started or stopped, the difference between the compressed air discharge amount and the usage amount can be quickly eliminated, and the pressure fluctuation can be suppressed.

  In the invention according to claim 3, the immediate decrease pressure is set to a lower pressure as the absolute value of the pressure change rate is larger, and the immediate increase pressure is set to a higher pressure as the absolute value of the pressure change rate is larger. The compressor number control system according to claim 2, wherein:

  According to the third aspect of the present invention, the immediately decreasing pressure and the immediately increasing pressure are made different according to the rate of change in pressure, and the threshold value of the pressure at which the compressor is additionally stopped or started at any time is changed. Thereby, the difference between the discharge amount and the use amount of the compressed air can be quickly eliminated, and the pressure fluctuation can be suppressed.

  According to a fourth aspect of the present invention, when a plurality of the compressors are operated at the same time, one is capacity-controlled, the other is fully loaded, and the compressed air from the compressors is shared. After being supplied to the receiver tank, it is sent to one or a plurality of compressed air utilization devices, and the pressure sensor is installed in the receiver tank, and the absolute value of the pressure change rate ΔP is less than the first set value ΔP1 Is stopped when the detected pressure P of the pressure sensor is equal to or higher than the second upper limit pressure PH2 as the pressure for decreasing the number of units, while one unit is started when the pressure is lower than the second lower limit pressure PL2 as the pressure for increasing the number of units. When the absolute value of the pressure change rate ΔP is not less than the first set value ΔP1 but less than the second set value ΔP2, the detected pressure P of the pressure sensor is the first upper limit pressure as the pressure for decreasing the number of units. PH1 or higher If one unit is stopped and still maintains the first upper limit pressure PH1 or more, one unit is stopped every time a predetermined continuous stop prevention time elapses, but the pressure for immediate decrease higher than the first upper limit pressure PH1. If the pressure exceeds the second upper limit pressure PH2, the other one is stopped without waiting for the elapse of the continuous stop prevention time, while the detected pressure P of the pressure sensor is the first lower limit pressure as the number increase pressure When the pressure falls below PL1, one unit is started, and when the first lower limit pressure PL1 is still maintained below, one unit is started every time the predetermined continuous start prevention time elapses. If the pressure is equal to or lower than the second lower limit pressure PL2 as the increasing pressure, another unit is started without waiting for the elapse of the continuous start prevention time, and the absolute value of the pressure change rate ΔP is set to the second set value Δ When the pressure in the receiver tank rises when the pressure in the receiver tank is equal to or higher than P2, one unit is stopped if the detected pressure P of the pressure sensor is equal to or higher than the first lower limit pressure PL1 as the pressure for reducing the number of units. When maintaining the pressure PL1 or higher, one unit is stopped every time the predetermined continuous stop prevention time elapses. However, the pressure PL1 must be higher than the first upper limit pressure PH1 as the immediately decreasing pressure higher than the first lower limit pressure PL1. For example, while the other stop is stopped without waiting for the elapse of the continuous stop prevention time, when the pressure in the receiver tank drops, the detected pressure P of the pressure sensor is the first upper limit pressure PH1 as the number increase pressure. If one unit is activated and the first upper limit pressure PH1 or less is maintained, one unit is activated every time a predetermined continuous activation prevention time elapses. 4. Another unit is started without waiting for the elapse of the continuous start prevention time when the pressure becomes equal to or lower than the first lower limit pressure PL1 as the immediately increasing pressure lower than the one upper limit pressure PH1. It is a compressor number control system of description.

  According to the fourth aspect of the present invention, it is easy to manufacture compressed air following the amount of compressed air used by controlling the capacity of one unit. Also, by changing the threshold value for starting or stopping the compressor according to the magnitude of the pressure change rate ΔP, the difference between the discharge amount and the usage amount of the compressed air can be quickly eliminated to suppress the pressure fluctuation. it can.

  Further, in the fifth aspect of the present invention, when the absolute value of the pressure change rate ΔP is equal to or larger than the second set value ΔP2, the detected pressure P of the pressure sensor is increased when the pressure in the receiver tank rises. When one lower limit pressure PL1 is exceeded, one unit is stopped. Even when the first lower limit pressure PL1 is maintained, the first unit is stopped every time a predetermined continuous stop prevention time elapses. If the pressure exceeds the first upper limit pressure PH1, the other one is stopped without waiting for the elapse of the continuous stop prevention time to become the second upper limit pressure PH2 higher than the first upper limit pressure PH1. 5. The compressor number control system according to claim 4, wherein the lock state of another full load operation is released.

  According to the fifth aspect of the present invention, when the pressure change rate is large and the pressure becomes higher than a predetermined value, the discharge amount and the usage amount of the compressed air are increased by increasing the number of compressors whose capacity is controlled. The pressure difference can be suppressed quickly by eliminating the difference.

  ADVANTAGE OF THE INVENTION According to this invention, the difference of the discharge amount of a compressor and the usage-amount of compressed air utilization apparatus can be corrected rapidly, and pressure fluctuation can be suppressed.

It is the schematic which shows one Example of the compressor number control system of this invention. It is a figure which shows an example of the number control method by the compressor number control system of FIG. 1, and has shown the discharge pressure of each compressor during a driving | operation, the pressure in a receiver tank, and a driving | operation number increase / decrease table.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram showing an embodiment of a compressor number control system according to the present invention. The compressor number control system 1 according to the present embodiment detects a plurality of compressors 2, 2,..., A receiver tank 3 to which compressed air is supplied from the compressor 2, and a pressure in the receiver tank 3. A pressure sensor 4 and a number controller 5 for controlling the compressors 2 based on the pressure detected by the pressure sensor 4 are provided.

  Each compressor 2 is an electric air compressor, and the compressor body is driven by a motor to suck, compress, and discharge outside air. Compressed air from each compressor 2 is sent to one or a plurality of various compressed air utilization devices (not shown) via a common receiver tank 3.

  Each compressor 2 is not particularly limited in its configuration, such as a screw type, a turbo type, or a reciprocating type, but typically has the same configuration as each other. Each compressor 2 typically has the same discharge capacity.

  Each compressor 2 of a present Example is comprised so that capacity | capacitance control is possible. Here, the capacity can be controlled mechanically by itself. Although the specific configuration of the capacity control is not particularly limited, in this embodiment, the capacity control is performed by adjusting the opening of a capacity adjustment valve (not shown) provided on the suction side of the compressor 2.

  A capacity | capacitance adjustment valve adjusts an opening degree by itself so that the pressure of the discharge side of the compressor 2 may be maintained as desired. In other words, as the pressure on the discharge side of the compressor 2 increases, the capacity adjustment valve reduces the suction amount by reducing the opening, thereby reducing the discharge amount while the compressor 2 reduces the discharge amount. As the pressure on the side decreases, the capacity adjustment valve increases the opening to increase the intake amount, thereby causing the compressor 2 to increase the discharge amount.

  More specifically, in FIG. 2, the capacity adjustment valve adjusts the opening so as to maintain the pressure on the discharge side of the compressor 2 between the lower limit pressure PL and the upper limit pressure PH. In this case, the capacity adjustment valve is fully opened when the pressure on the discharge side of the compressor 2 is lower than the lower limit pressure PL, and is fully closed when the pressure is higher than the upper limit pressure PH. Further, the opening degree is proportionally reduced between the lower limit pressure PL and the upper limit pressure PH as it goes from the lower limit pressure PL to the upper limit pressure PH. Thus, the pressure range between the lower limit pressure PL and the upper limit pressure PH is the control range of the capacity adjustment valve. If the pressure on the discharge side of the compressor 2 exceeds a predetermined stop pressure PS, the compressor 2 is forcibly stopped.

  Each compressor 2 of a present Example is provided with the full load lock function for hold | maintaining to full load (full load) driving | operation. When the full load is locked, the capacity adjustment valve is held fully open, and the compressor 2 operates at full load. Therefore, in the present embodiment, each compressor 2 is operated at full load in a state where the full load is locked, while capacity is controlled by the capacity adjustment valve in a state where the full load lock is released. The presence / absence of operation of each compressor 2 and the presence / absence of full load lock can be individually set for each compressor 2 by the number controller 5.

  The receiver tank 3 is a hollow container that is supplied with compressed air from each compressor 2 and supplies compressed air to one or a plurality of compressed air using devices. A pressure sensor 4 is provided so that the pressure in the receiver tank 3 can be detected.

  The number controller 5 is connected to each compressor 2 and the pressure sensor 4, and controls each compressor 2 based on the pressure detected by the pressure sensor 4. In the present embodiment, the presence / absence of operation of each compressor 2 (that is, the change in the number of operating units) and the presence / absence of full load lock of the compressor 2 during operation are switched. A specific control method is as follows.

  FIG. 2 is a diagram showing an example of the number control method by the compressor number control system 1 of the present embodiment. The discharge pressure of each compressor 2 during operation and the pressure in the receiver tank 3 (that is, the pressure sensor 4) Detection pressure) and the number of operating units increase and decrease table. The operating number increase / decrease table shows how the compressor 2 is started / stopped based on the pressure P in the receiver tank 3 and the rate of change ΔP, in other words, how the operating number is increased / decreased. This control is performed based on the detected pressure P of the pressure sensor 4 and the pressure change rate ΔP at predetermined intervals. In the present embodiment, an average value for a predetermined number of times (for example, 20 times) of the calculation cycle of the CPU of the number controller 5 is used as the detected pressure P, and the most recent predetermined time (for example, the latest 20 seconds) is used as the pressure change rate ΔP. ) Average value is used.

  The pressure change rate ΔP is a fluctuating pressure per predetermined time. When the pressure change rate ΔP is negative, the pressure in the receiver tank 3 tends to decrease, and when the pressure change rate ΔP is positive, the pressure in the receiver tank 3 tends to increase. When the amount of compressed air used by the device using compressed air is larger than the amount of compressed air discharged by the compressor 2, the pressure in the receiver tank 3 decreases, and conversely, the amount of compressed air discharged by the compressor 2 is When the amount of compressed air used is greater than the amount of compressed air used by the device using compressed air, the pressure in the receiver tank 3 increases.

  Due to the pressure loss of the piping from the compressor 2 to the receiver tank 3, the pressure in the receiver tank 3 is slightly lower than the discharge pressure of the compressor 2. Therefore, as shown in FIG. 2 by connecting with broken lines having a slight inclination, the pressures PL1, PL2, PH1, and PH2 in the receiver tank 3 are the discharge pressures PL1 ′, PL2 ′, PH1 ′, and PH2 of the compressor 2, respectively. Corresponds to '.

  The number controller 5 compares the detected pressure P of the pressure sensor 4 with a preset pressure value, and increases or decreases the number of operating compressors 2. At this time, the pressure value for changing the number of operating units is preferably set to be different based on the pressure change rate ΔP of the pressure detected by the pressure sensor 4.

  That is, first, the number controller 5 stops one compressor 2 when the detected pressure P of the pressure sensor 4 becomes equal to or greater than the pressure A for decreasing the number, while the detected pressure P of the pressure sensor 4 is equal to or less than the pressure B for increasing the number. Then, one compressor 2 is started. Preferably, the number-decreasing pressure A as a boundary value for determining whether or not the number of operating units is decreased by the number controller 5 is set so as to gradually decrease as the pressure change rate ΔP increases to the plus side. . Further, the number-increasing pressure B as a boundary value for determining whether or not to increase the number of operating units by the number controller 5 is set so as to increase gradually as the pressure change rate ΔP increases to the minus side.

  Then, the number controller 5 determines a predetermined time (continuous stop prevention time, continuous start prevention time) when the detected pressure P of the pressure sensor 4 maintains a state where the detected pressure P is greater than the number decrease pressure A or less than the number increase pressure B. Each time the compressor 2 passes, one compressor 2 is stopped or started. In the region where the absolute value | ΔP | of the pressure change rate ΔP is equal to or larger than the set value (ΔP1), the detected pressure P of the pressure sensor 4 immediately decreases. When the pressure becomes equal to or higher than the operating pressure C or equal to or lower than the immediate increase pressure D, one more apparatus is stopped or one is started without waiting for the elapse of the predetermined time. The immediate decrease pressure C is preferably set to be lower as the absolute value of the pressure change rate ΔP is larger, and the immediate increase pressure D is preferably set to be higher as the absolute value of the pressure change rate ΔP is larger. Further, the continuous stop prevention time and the continuous activation prevention time may be different from each other or the same.

  In the present embodiment, the unit controller 5 controls the capacity of one unit 2 when operating only one compressor 2, while the unit controller 5 controls one unit when operating a plurality of compressors 2 at the same time. The capacity is controlled and the others are operated at full load. At this time, the capacity of the compressor 2 activated first is controlled, and the subsequent compressor 2 is operated at full load. Therefore, when there is a compressor 2 that is already in operation, when the number of operating units is increased, the full load operation compressor 2 is added. Conversely, when reducing the number of operating units while operating a plurality of compressors 2, the starting machine (the compressor 2 that was started first) that had been capacity-controlled until then was stopped, instead. The next engine (the compressor 2 activated second) is switched to capacity control. Thereafter, the capacity of this next machine is controlled as the first machine, and the priority when stopping is the highest.

  Hereinafter, specific control using the pressure P in the receiver tank 3 and the rate of change ΔP thereof will be described with reference to FIG. The second lower limit pressure PL2 is set lower than the first lower limit pressure PL1, the second upper limit pressure PH2 is set higher than the first upper limit pressure PH1, and the first lower limit pressure PL1 and the second lower limit pressure PL2 are The first upper limit pressure PH1 and the second upper limit pressure PH2 are set to a lower pressure. Furthermore, the pressure between the first lower limit pressure PL1 and the first upper limit pressure PH1 corresponds to or includes the control range PL to PH of the capacity adjustment valve of each compressor 2. Each set value ΔP1, ΔP2 is set in consideration of the discharge capacity during full load operation for one compressor.

(1) When the absolute value of the pressure change rate ΔP is less than the first set value ΔP1 (| ΔP | <ΔP1). Specifically, when -ΔP1 <ΔP <+ ΔP1.
When the detected pressure P of the pressure sensor 4 becomes equal to or higher than the second upper limit pressure PH2 as the pressure A for decreasing the number of units, one unit is stopped. As a result, the pressure is normally lower than the second upper limit pressure PH2, but if the use load of compressed air continues to decrease during this time, the pressure may maintain the second upper limit pressure PH2 or more. In that case, every time the predetermined continuous stop prevention time elapses, one compressor 2 is stopped. That is, when the detected pressure P of the pressure sensor 4 remains in the “one unit stop” region in FIG. 2, the unit is stopped one by one every time the continuous stop prevention time elapses as long as the compressor 2 is operating.

  Conversely, when the detected pressure P of the pressure sensor 4 becomes equal to or lower than the second lower limit pressure PL2 as the number increase pressure B, one unit is activated. As a result, the pressure normally exceeds the second lower limit pressure PL2, but if the use load of compressed air continues to increase during this time, the pressure may remain below the second lower limit pressure PL2. In that case, every time the predetermined continuous activation prevention time elapses, one compressor 2 is activated. That is, when the detected pressure P of the pressure sensor 4 remains in the “one unit start” region in FIG. 2, as long as there is a compressor 2 that is stopped, one unit is started each time the continuous start prevention time elapses.

(2) When the absolute value of the pressure change rate ΔP is not less than the first set value ΔP1 but less than the second set value ΔP2 (ΔP1 ≦ | ΔP | <ΔP2). Specifically, when + ΔP1 ≦ ΔP <+ ΔP2 or −ΔP2 <ΔP ≦ −ΔP1.
When the detected pressure P of the pressure sensor 4 becomes equal to or higher than the first upper limit pressure PH1 as the pressure A for decreasing the number of units, one unit is stopped. Also in this case, when the first upper limit pressure PH1 is maintained even if one unit is stopped, one unit is stopped every time a predetermined continuous stop prevention time elapses, but the second upper limit pressure PH2 as the immediate decrease pressure C is used. If it becomes above, another one is stopped, without waiting for progress of the continuous stop prevention time.

  That is, in FIG. 2, even if one unit is stopped by entering the “stop one” area, if it still remains in that area, 1 is set for each continuous stop prevention time as long as there is a compressor 2 in operation. Stop the compressor 2 one by one. In the meantime, if the “additional one stop” area is entered, even if the continuous stop prevention time does not elapse, another one is stopped.

  Conversely, when the detected pressure P of the pressure sensor 4 becomes equal to or lower than the first lower limit pressure PL1 as the number increase pressure B, one unit is activated. Also in this case, when one unit is started and the first lower limit pressure PL1 or less is maintained, one unit is started every time a predetermined continuous start prevention time elapses, but the second lower limit pressure PL2 as the immediate increase pressure D is used. If it becomes below, another one is started, without waiting for progress of continuous starting prevention time.

  That is, in FIG. 2, if one unit is started by entering the “one unit start” region and still remains in that region, it remains 1 every continuous start prevention time as long as there is a compressor 2 being stopped. The compressor 2 is started one by one. In the meantime, if the “one more unit activation” area is entered, one unit is activated even if the continuous activation prevention time has not elapsed.

(3) When the absolute value of the pressure change rate ΔP is greater than or equal to the second set value ΔP2 (| ΔP | ≧ ΔP2). Specifically, when ΔP ≧ + ΔP2 or ΔP ≦ −ΔP2.
When the pressure in the receiver tank 3 rises (when the pressure change rate ΔP is positive, that is, ΔP ≧ + ΔP2), the detected pressure P of the pressure sensor 4 is equal to or higher than the first lower limit pressure PL1 as the pressure A for decreasing the number of units. And stop one. Also in this case, when the first lower limit pressure PL1 is maintained even if one unit is stopped, one unit is stopped every time a predetermined continuous stop prevention time elapses, but the first upper limit pressure PH1 as the immediate decrease pressure C is used. If it becomes above, another one is stopped, without waiting for progress of the continuous stop prevention time. If the pressure reaches the second upper limit pressure PH2 or more, the other full load lock state is released.

  That is, even if one unit is stopped by entering the “stop one” region in FIG. 2 and still remains in that region, one unit for each continuous stop prevention time as long as there is a compressor 2 in operation. The compressor 2 is stopped one by one. In the meantime, if the “additional one stop” area is entered, even if the continuous stop prevention time does not elapse, another one is stopped. Furthermore, if the “full load lock release” area is entered, if there is a compressor 2 that is operating at full load, then one full load lock state is released.

  In the “full load lock release” area, a total of two compressors 2 are under capacity control (since one is under capacity control before that), but the detected pressure P of the pressure sensor 4 is the second upper limit. When the pressure is less than PH2 or the pressure change rate ΔP is less than + ΔP2, one of them is returned to the full load lock state, that is, full load operation.

  On the contrary, when the pressure in the receiver tank 3 drops (when the pressure change rate ΔP is negative, that is, ΔP ≦ −ΔP2), the detected pressure P of the pressure sensor 4 is the first upper limit pressure as the pressure B for increasing the number of units. If it is less than PH1, one unit is activated. In this case as well, when the first upper limit pressure PH1 or less is maintained even when one unit is started, one unit is started every time a predetermined continuous start prevention time elapses, but the first lower limit pressure PL1 as the immediate increase pressure D is used. If it becomes below, another one is started, without waiting for progress of continuous starting prevention time.

  That is, even if one unit is started by entering the “one unit start” area in FIG. 2 and still remains in that region, as long as there is a compressor 2 that is stopped, one unit for each continuous start prevention time The compressor 2 is started one by one. In the meantime, if the “one more unit activation” area is entered, one unit is activated even if the continuous activation prevention time has not elapsed.

  According to the compressor number control system 1 of the present embodiment, the difference between the amount of compressed air discharged by the compressor 2 and the amount of compressed air used by the compressed air utilization device is captured by the pressure change rate, and the pressure change rate ΔP is When it is larger, the threshold value of the pressure for starting or stopping the compressor 2 is changed. In addition, the continuous startup or stop of the compressor 2 is performed with a predetermined delay time, but in a region where the pressure change rate ΔP is large, the pressure decreases immediately above the pressure C for immediate decrease or below the pressure D for immediate increase. If it is, one unit is stopped or one unit is started without waiting for the elapse of a predetermined time. Thereby, the difference between the discharge amount and the use amount of the compressed air can be quickly eliminated, and the pressure fluctuation can be suppressed.

  The compressor number control system 1 of the present invention is not limited to the configuration of the above-described embodiment, and can be changed as appropriate. For example, each compressor 2 may have an unloader function. In that case, in the embodiment, the compressor 2 may be started and stopped by loading and unloading the compressor 2.

  In the above embodiment, when a plurality of compressors 2 are operated at the same time, the capacity of one unit is controlled and the other is fully loaded, but the capacity control method is the same as in the above embodiment. 2 is not limited to the capacity adjustment valve provided on the suction side, and other conventionally known configurations may be employed. Further, all the compressors 2 may be simply subjected to on / off control and load / unload control without capacity control.

  Moreover, in the said Example, although the compressed air from each compressor 2 was sent to the apparatus using compressed air via the receiver tank 3, and the pressure sensor 4 was provided in the receiver tank 3, in addition to the receiver tank 3, each compression The pressure sensor 4 may be provided at a location where the compressed air is supplied from the machine 2 or a location where the compressed air is sent to the device using the compressed air.

  Furthermore, in the said Example, although each compressor 2 was set as the mutually same structure and discharge capacity, you may make these differ depending on the case. In the number increase / decrease table of FIG. 2, the pressure change rate on the horizontal axis is divided into five regions, but the number of regions can be increased or decreased as appropriate. Similarly, although the pressure on the vertical axis is divided into the first lower limit pressure PL1, the first upper limit pressure PH1, the second lower limit pressure PL2, and the second upper limit pressure PH2, this can also be increased or decreased as appropriate.

DESCRIPTION OF SYMBOLS 1 Compressor number control system 2 Compressor 3 Receiver tank 4 Pressure sensor 5 Number controller A Number of pressure reduction B Number of pressure increase C Immediate decrease pressure D Immediate increase pressure

Claims (5)

Multiple compressors,
A pressure sensor for detecting the pressure of the compressed air, which is provided at a location where the compressed air is supplied from these compressors and the compressed air is sent to the device using the compressed air;
A unit controller for changing the number of operating compressors based on the pressure detected by the pressure sensor and the rate of change in pressure,
The number controller stops one compressor when the detected pressure of the pressure sensor becomes equal to or higher than the pressure for decreasing the number, while one compressor is detected when the detected pressure of the pressure sensor becomes equal to or lower than the pressure for increasing the number. Start
If the detected pressure of the pressure sensor is still above the pressure for decreasing the number or below the pressure for increasing the number, the compressor is stopped or started every time a predetermined time elapses. In the region where the absolute value of the change rate is greater than or equal to the set value, if the detected pressure of the pressure sensor becomes equal to or higher than the pressure for immediate decrease or equal to or less than the pressure for immediate increase, one more unit is stopped without waiting for the predetermined time Alternatively, a compressor number control system characterized by starting one. The pressure for reducing the number of vehicles as a boundary value whether or not to reduce the number of operating units by the number controller is set so as to decrease as the pressure change rate increases to the plus side,
The number increase pressure as a boundary value of whether to increase the number of operating units by the number controller is set to increase as the pressure change rate increases to the negative side,
When the detected pressure of the pressure sensor becomes equal to or higher than the pressure for reducing the number of units, one compressor is stopped, and when the pressure for reducing the number of units is still maintained, the compressor is stopped every time a predetermined continuous stop prevention time elapses. In the region where the absolute value of the pressure change rate is equal to or greater than the set value, the continuous stop prevention time has elapsed if the pressure decreases more than the immediate decrease pressure set higher than the unit decrease pressure. Stop one more without waiting for
When the detected pressure of the pressure sensor becomes equal to or lower than the pressure for increasing the number of units, when one compressor is started and still maintains the pressure for increasing the number of units or less, the compressor is compressed each time a predetermined continuous start prevention time elapses. In the region where the absolute value of the rate of change in pressure is greater than or equal to the set value, the continuous start prevention time has elapsed if the pressure is less than the immediate increase pressure set lower than the unit increase pressure. The system for controlling the number of compressors according to claim 1, wherein one more unit is started without waiting. The immediately decreasing pressure is set to a lower pressure as the absolute value of the pressure change rate is larger,
The system for controlling the number of compressors according to claim 2, wherein the immediate increase pressure is set to a higher pressure as the absolute value of the pressure change rate is larger. When a plurality of compressors are operated at the same time, one of the compressors is capacity-controlled, the other is operated at full load,
Compressed air from each of the compressors is supplied to a common receiver tank and then sent to one or more compressed air utilization devices,
The pressure sensor is installed in the receiver tank,
When the absolute value of the pressure change rate ΔP is less than the first set value ΔP1, when the detected pressure P of the pressure sensor becomes equal to or higher than the second upper limit pressure PH2 as the number reduction pressure, one unit is stopped, When it becomes below the second lower limit pressure PL2 as the pressure for increasing the number of units, one unit is started,
When the absolute value of the pressure change rate ΔP is not less than the first set value ΔP1 but less than the second set value ΔP2,
When the detected pressure P of the pressure sensor becomes equal to or higher than the first upper limit pressure PH1 as the number-decreasing pressure, one unit is stopped, and if the first upper limit pressure PH1 is still maintained, the predetermined continuous stop prevention time elapses. However, if the pressure becomes equal to or higher than the second upper limit pressure PH2 as the immediately decreasing pressure, which is higher than the first upper limit pressure PH1, another unit is stopped without waiting for the continuous stop prevention time to elapse. While letting
When the detected pressure P of the pressure sensor becomes equal to or lower than the first lower limit pressure PL1 as the number-increasing pressure, one unit is activated, and when the first lower limit pressure PL1 is still maintained, the predetermined continuous activation prevention time elapses. However, if the pressure becomes equal to or lower than the second lower limit pressure PL2 as the immediately increasing pressure, which is lower than the first lower limit pressure PL1, one more unit is started without waiting for the continuous start prevention time to elapse. ,
When the absolute value of the pressure change rate ΔP is greater than or equal to the second set value ΔP2,
When the pressure in the receiver tank rises, if the detected pressure P of the pressure sensor is equal to or higher than the first lower limit pressure PL1 as the number reduction pressure, one unit is stopped, and still maintains the first lower limit pressure PL1 or higher. One unit is stopped every time a predetermined continuous stop prevention time elapses, but when the pressure exceeds the first upper limit pressure PH1 as the immediately decreasing pressure higher than the first lower limit pressure PL1, the continuous stop prevention time is increased. While stopping another one without waiting for progress,
When the pressure in the receiver tank drops, if one of the pressure sensors detected pressure P is less than or equal to the first upper limit pressure PH1 as the number increase pressure, one unit is activated, and still maintains the first upper limit pressure PH1 or less, Each time a predetermined continuous activation prevention time elapses, one unit is activated, but if the pressure does not exceed the first lower limit pressure PL1 as the immediately increasing pressure, which is lower than the first upper limit pressure PH1, the continuous activation prevention time is increased. The compressor number control system according to claim 3, wherein another unit is started without waiting for the progress. When the absolute value of the pressure change rate ΔP is greater than or equal to the second set value ΔP2, when the pressure in the receiver tank rises, one unit stops if the detected pressure P of the pressure sensor is greater than or equal to the first lower limit pressure PL1. However, when maintaining the first lower limit pressure PL1 or higher, one unit is stopped every time the predetermined continuous stop prevention time elapses, but the first upper limit pressure PH1 higher than the first lower limit pressure PL1 must be exceeded. For example, if another unit is stopped without waiting for the elapse of the continuous stop prevention time and becomes equal to or higher than the second upper limit pressure PH2, which is higher than the first upper limit pressure PH1, then another full load operation is performed. The compressor state control system according to claim 4, wherein the locked state is released.

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